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Old 04-26-2012, 05:38 AM   #1
boosted88mkIII
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Default how much boost can a stock 7mgte hold??

just wondering if anyone knew how much boost a bone stock 7mgte can hold and the best way to get it?? I've seen shimmed waste gate but that's a little sketchy to me... any tips
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Old 04-26-2012, 05:53 AM   #2
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Bone stock you'll see about 6 PSI of boost. To get more than that, you can upgrade your exhaust, install a boost controller, upgrade the turbo, shim the wastegate (I personally don't recommend this method).... Basically, there are several different methods to increase boost pressure. I believe the easiest way to gain more boost would be to buy or construct a manual boost controller. This method also allows you to adjust the amount of extra boost, depending on your needs.

With all that said, I wouldn't recommend running much extra boost on a tired 24 year old engine; extra boost equals higher combustion chamber pressure and stress, which typically exposes hidden problems (such as a weak head gasket). Make sure your engine is healthy and in good running condition before trying to force more power from it.
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Old 04-26-2012, 03:27 PM   #3
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iv heard about shimmiying the wasegate and read about it on the faq's but has anyone done it and would like to give me there opinion on it

a healthy 7mgte can handle 12psi on a factory turbo right? i think i read that if you push much more out of it your looking for trouble
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Old 04-26-2012, 06:11 PM   #4
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Quote:
Originally Posted by pandrade View Post
iv heard about shimmiying the wasegate and read about it on the faq's but has anyone done it and would like to give me there opinion on it
a healthy 7mgte can handle 12psi on a factory turbo right? i think i read that if you push much more out of it your looking for trouble
the general opinion on the shimming is retarded.. when there are safer ways.. for instance.. 12 bucks gets you a manual boost controller..

as for safe boost.. anything above 12 and your looking at forged internals..
granted everything is in top shape..

your sig says 135k miles on a stock platform.. I wouldn't shoot for 12 less you restore your engine first. 20 years is 20 years.. no matter how much you babied your car.
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Old 04-26-2012, 06:27 PM   #5
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Quote:
Originally Posted by pandrade View Post
iv heard about shimmiying the wasegate and read about it on the faq's but has anyone done it and would like to give me there opinion on it

a healthy 7mgte can handle 12psi on a factory turbo right? i think i read that if you push much more out of it your looking for trouble
When I got my first 87 turbo, it had a shimmed wastegate. It worked just fine, but it causes extra stress on the wastegate actuator diaphragm and I'm sure other parts. Unneeded stress when, as Green mentioned above, there are easier and safer methods to achieve the extra boost.
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Old 04-26-2012, 06:38 PM   #6
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Agreed. Shimming the waste gate isn't just retarded but it's also hazardous. For every millimeter you shim out the actuator you remove a similar degree of motion from the wastegate's toatal allowable travel distance steadily increasing the risk of boost creep. On the upside, unless you're running a poorly setup FCD, you'll just hit boost cut but that's still no fun and if you're on it hard enough that may not kick in soon enough.

I need to go through the FAQ and remove the references on shimming or annote them all.... Oh goody, more work.

If you want to build a cheap boost controller on your own google "grainger boost controller".

Addendum:
I can't find any FAQ on shimming the wastegate. Anyone care to provide me a link with where they are finding this? I'm sure it's in a thousand and one threads throughout the forum but I'm not going to edit all of those. I just don't want it in the FAQ sections.
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Old 04-26-2012, 09:39 PM   #7
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this is the link on the FAQ'S that tells about shimmying the waste gate

http://www.toyota-supra.info/forums/...-websites.html

then click on this one www.SUPRAS.com - Member's Section

i wouldent take it off the FAQ's alot of other good thinks on that link i would warn about the bad effects of shimmying the waste gate , or maby make a FAQ page of most common mk3 and 7mgte myth's which would cover this

and on a side note does any one know of a good manual boost controller they would recomend
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Last edited by pandrade; 04-26-2012 at 09:46 PM.
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Old 04-27-2012, 12:08 AM   #8
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That thread doesn't mention shimming the wastegate and no, I'm not going to remove the link to an entire site because they happen to have one antiquated article on the concept.

I guess I'll try to make time to put together a short thread on boost control methods soon. I'm in the process of buying, renovating and moving to a new house so time is getting harder and harder to come by.
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Old 04-27-2012, 12:22 AM   #9
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dont know how you can find the time to keep this fourm running as well as it does, work and move lol
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Old 04-27-2012, 12:42 PM   #10
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oh you don't know this. but cre actually has 4 hands.. and telekinesis.
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